1. Field of the Invention
This invention relates generally to diode-pumped solid state UV laser systems, and their methods of use, and more particularly to diode-pumped solid state UV laser systems that are used in micro-machining of polymeric articles.
2. Description of Related Art
The increasing demand for electronic devices is driving the need for laser materials processing in microelectronics industry. Among a wide variety of laser applications, micro-machining of polymers using diode-pumped solid-sate (DPSS) UV lasers is gaining more and more attention. Due to the short wavelengths (355 nm or 266 nm) of UV lasers, small feature size and minimum thermal damage, both the desired features of miniaturized devices, can be obtained.
However, compared with the processes using lasers of longer wavelength such as CO2 lasers, those using UV lasers are generally slower. So there is a constant effort to increase the processing speed and thus increase the throughput of production processes involving UV lasers.
Most DPSS UV lasers currently used in electronics industry are Q-switched lasers with pulsewidths ranging from 5 ns to 100 ns and pulse repetition rates ranging from 1 kHz to 100 kHz. A 355 nm mode locked laser at 8 MHz repetition rate produces an average power of 4 W at output, with a repetition rate of 80 MHz and a pulsewidth of 10 ps. It is expected that the mode-locked laser can provide certain unique advantages in laser micro-machining of certain materials due to its ultrafast pulse and high repetition rate.
There is a need for a diode-pumped solid-state laser that can cut or scribe polymer materials at an increased speed.
Accordingly, an object of the invention is to provide an improved micro-machining apparatus, and its method of use.
Another object of the present invention is to provide a diode-pumped solid state laser, and its method of use, that can cut or scribe polymer materials at increased speeds.
These and other objects of the present invention are achieved in a micro-machining apparatus. The apparatus includes a mode-locked, infrared laser system with a high reflector and an output coupler that define an oscillator cavity which produces an output beam. A gain medium and a mode locking device are positioned in the oscillator cavity. A diode pump source produces a pump beam that is incident on the gain medium. A second harmonic generator is coupled to the oscillator cavity. A third harmonic generator is coupled to the second harmonic generator and produces a UV output beam. An output beam directing apparatus directs the output beam to a polymeric surface of an article. At least a portion of the polymeric material is micro-machined by the output beam.
In another embodiment of the present invention, a micro-machining apparatus includes a mode-locked, infrared laser system with a high reflector and an output coupler that define an oscillator cavity. The oscillator cavity produces an output beam. A gain medium and a mode locking device are positioned in the oscillator cavity. A diode pump source produces a pump beam that is incident on the gain medium and a first amplifier. A second harmonic generator is coupled to the oscillator cavity. A third harmonic generator is coupled to the second harmonic generator and produces a UV output beam. An output beam directing apparatus directs the output beam to a polymeric surface of an article. At least a portion of the polymeric material is micro-machined by the output beam.
In another embodiment of the present invention, a method of micro-machining a polymeric surface of an article provides a mode-locked, infrared laser system that includes a high reflector and an output coupler which define an oscillator cavity. A gain medium and a mode locking device are positioned in the oscillator cavity. A UV output beam is produced from the laser system. The UV output beam is then used to micro-machine at least a portion of the polymeric surface of the article.